Woodworking machine with automatically movable cutter-carrying frame



Apnl 22, 1952 F. H. GILLESPIE 2,593,744

WOODWORKING MACHINE WITH AUTOMATICALLY MOVABLE CUTTER-CARRYING FRAME Filed Dec. 5, 1946 4 Sheets-Sheet l Q fiezsrfl 6/4455/ /5, N INVENTOR.

Afro/awn:

Apnl 22, 1952 F. H. GILLESPIE 2,593,744

WOODWORKING MACHINE WITH AUTOMATICALLY I MOVABLE CUTTER-CARRYING FRAME Filed Dec. 5, 1946 4 Sheets-Sheet 2 FIG. 2

F. H. GILLESPIE 2,593,744

WOODWORKING MACHINE WITH AUTOMATICALLY MOVABLE CUTTER-CARRYING FRAME April 22, 1952 4 Sheets-Sheet .3

Filed Dec. 5, 1946 FIG. 3.

Foe 557 64 64:55pm,

INVENTOR.

Afro/awn April 22, 1952 F. H. GILLESPIE 2,593,744

WOODWORKING MACHINE WITH AUTOMATICALLY MOVABLE CUTTER-CARRYING FRAME Filed Dec. 5, 1946 4 Sheets-Sheet 4 F'oezsrbf 6am-5pm;

- INVENTOR.

HTTOENEK Patented Apr. 22, 1952 ESTATES PATENT WOODWORKING MACHINE IWrrH, AUTO- MATICALLY MOVABLE CUTTER-CARRY- ING FRAME Forest H. Gillespie,'Los Angele's, Calif. Application December 5, 1946, Serial No, 714,172

The present invention relates to woodworking machines in general and particularly to a woodworking machine capable of performing a plurality of operations upon a work piece simultaneously. More specifically the invention comprises "a woodworking machine for making simultaneously dove tail ends and for providing handle holes in a drawer panel.

In the manufacture of wooden products, including articles of furniture, the time required to perform the various pre-assembly operations is an important factor in the final cost. In large scale production the same operation is performed over and over again on pieces of -the same kind which may then be subjected either to further op- I erations or to assembly with other elements. The time required for each piece to pass through a particular operation determines how many pieces can be handled in a given time period which in turn determines the output.

The apparatus comprising the present invention is designed to perform several operations simultaneously upon a wooden piece and to repeat that operation upon successive wooden pieces as they are placed in the machine. The wooden piece or member is preferably a flat element and is cut at its ends to provide dove tailed ends by which it may be interlockingly joined to similarly conditioned elements. Simultaneously it is drilled between its ends in order that hardware elements may be attached, as for example bolts, handles, etc; After the piece to be operated upon is placed upon the working table of the machine the operator need only actuate certain controls whereupon the machine automatically performs its various functions and returns to its initial condition in which it is ready'tooperate upon the following piece. i

It is an object of the present inventionto provide a new and improved woodworkingmachine in which a plurality of distinct operations are simultaneously performed upon a single piece of work. 7

It is another object of the invention to provide a semi-automatic woodworking machine in which end surfaces of the work and intermediate portions thereof are simultaneously acted upon.

Still another object of the invention is to provide a Woodworking machine in which -a flat wooden member is provided with'dove tailed ends and is simultaneously drilled at a mid point A further object of the invention comprises the provision of a semi-automatic woodworking machine in which the operator need only position the work piece and thereafter actuate the machine controls to initiate an' operation in which the piece is provided with opposed dove tail ends and is drilled intermediate the ends;

These and other more specific objectsewill appear upon readingthe following specification and 17 Claims. (01. 144-4 2 claims and upon considering in connection therewith the attached drawings to which they relate.

Referring now to the drawings in which a preferred embodiment of the invention is illustrated:

Figure l is a side elevation of a woodworking machine constructed in accordance with the present invention;

Figure '2 is a front view of the machine illustrated in Figure 1; I

Figure 3 is a view looking downwardly on the machine upon the line 3--3 of Figure 1;

Figure 4 (sheet 2) is a partial section upon the line 4-4 of Figure 2 and illustrates a part of the control mechanism for the means which form the dove tail ends; 7 c c Figure 5 is a front view of the structure shown inFigure 4;

Figure 6 is a view-of the drilling means and its control removed from the complete machine; and

Figure 7 is a view in perspective of a board which has been processed in the machine.

The machine in generdl The Woodworking machine constructed in accordance with the present invention, and as illustrated in a preferred embodiment in the drawings, may be viewed as comprising five primary functionally related parts, as follows: 7

1. The mean for clamping the work piece.

2. The means for forming the dove tail ends upon the work piece. I

3. The means for drilling the central handle holes. h V

4. The coordinating means.

5. The machine frame. I

, These features will now be discussed individually, the machine frame being discussed first as the other parts are related to and carried thereby.

The machine frame The frame or framework of the woodworking machine constructed in accordance with the present invention is simply constructed of strong members, preferably metallic, and is indicated generally by the reference character ll. Vertical upright elements or legs I2 are positioned at its four corners and are interconnected by suitable similarly sectioned side and end members I3 and I4 upon two levels to form an upper level or work table, indicated generally by the reference character I6, and a lower level or platform, indicated generally by the reference character I1. Other intermediate structural elements are included to supplement the basic framework described and upon which certain operative parts of the machine are mounted.

The means for clamping the work piece Theboard to be worked upon, indicated in the drawings by the character B, is supported in the position to be worked upon by a plate or base l8 thereof in similar means 46.

carried by frame end member l4 and by an intermediate cross member [9. An apron 2| extends forwardly from the forward end member l4 and provides a delivery and receiving platform for boards before and after they are operated upon. A transverse abutment member 22 is suitably secured by bolts 23 to support base l8 and serves to align the board upon its insertion in cooperation with guide members 24 and 25 which it carries and which abut and overlie the opposite ends, respectively. Actually the guide element 24 contacts only the upper part of the end board B, as is clearly illustrated in Figure 2, thereby leaving both ends exposed for the larger part of their areas.

As the board is to be operated upon by positively driven elements, it is necessary that it be firmly held in place. To accomplish this clamp members 21 are provided upon each side of the boards center forward of the abutment member 22 and are vertically movable from the clamping position illustrated in the drawings through being pivotally supported upon a transversely extending rock shaft 29 by interconnected arms 28. The shaft 29 is supported for arcuate rotary movement by bearings 3| at its ends positioned upon vertically extending brackets 32, the bases of which are themselves supported upon the side frame members |3 for longitudinal adjustment by cooperative bolt and slot connections indicated generally at 33. Different sizes of boards B could require that the clamps 21 be altered somewhat in their positions and the adjustable are raised, the adjustment being accomplished by the rocking of the shaft 29 under the pivotal force exerted by lever arm 34 fixed thereto which is itself controlled by means hereinafter discussed underthe title Coordinating Means.

The means for forming the dope tail ends With the board firmly clamped in position as illustrated it is ready to be worked upon by cutters 4| rotatably mounted upon adjustable panels or frames 42 of which there are two, one at each end of the board B. There are in fact a battery of rotary cutters 4| mounted upon each panel 42 and they extend in parallel spaced relationship with their upper ends reachingabove the panel so that in one angular position of the latter, as illustrated in Figure 5, they cut into the ends of the board B to form dove tail grooves therein. Each cutter'4l includes an extended shaft 43 rotatably mounted at the upper end of the panel in a suitable mounting 44 and at the lower end Midway between its ends each cutter shaft carries a gear 41 which meshes with a similar gear carried upon the adjacent cutter shaft 43so that the rotation of one effects the rotation of all and at synchronous speeds. A driving gear 48, carried by a shaft 49, and two are illustrated for each panel or frame 42, meshes with one of the individual gears 41 to drive the chain. Each shaft 49 is suitably supported in journals secured to the panel or frame 42 and each carries a pinion 52 at its lower end in mesh with a gear 53 fixed to a longitudinally extending shaft 54 rotatably supported in journals 56 on the frame.

Shaft 54 transmitting power for the cutters 4| on each panel 42 is driven from a drive shaft 51 itself connected through a multiple belt and axially slidable member 66, the two members being suitably connected by universal joints 61 and 68, respectively, to the drive shaft 51 and to the driven shaft 54. Regardless of the angular position of the cutter-carrying frame 42, the connection 63 positively insures the rotation of the shaft 54 upon the rotation of the shaft 51.

Each panel or frame 42 must be movable between an inoperative position, as illustrated in Figure 2, and a working operative position, illus-" trated in Figure 5. To provide for this movement each panel is carried by a transverse axle 1| rotatably seated in journals 12 and supported at each end by a gear 13 riding adjusta'bly in a toothed rack 14. A second look rack 16 is removably connected between spaced vertical leg members I2 and contacts the upper portion of the gears 13 to secure them in selected positions determining the spacing of the panels 42 and in which they are adapted to be positioned readily by the use of the handle 15, shown in Figure 1,

'when the lock rack 16 is removed. Each panel is adapted to pivot about its supporting shaft 1| as an axis, its upper end at which the cutters 4| are positioned being movable toward or from the adjacent end of the board B in a relationship which is clearly illustrated in Figure 2.

The mechanism by which the panels are actuated at the proper time intervals will be hereinafter described under the title Coordinating Means.

Means for drilling the central handle holes In addition to the provision of dove tail ends upon the board B, means are also provided for the drilling of holes suitable for the attachment of handles midway between its ends. These means comprise spaced drills, indicated generally by the reference character 16, each comprising a rotatable bit11 removably seated in a chuck 18 at the lower end of a rotatable shaft 19 mounted for rotation in housing 8|. The backs 62 of the housings are channeled, as at 83, to seat for slidingmovement upon a laterally extending seat 84 formed upon a support 86. The latter is suitably mounted for vertical reciprocation u-pon end blocks 81 carried by the aforementioned vertically extending brackets 32.

Each drill shaft 19 is provided with a pulley 9| atits upper end and these are connectedby belts 92 to pulleys carried by a transversely extending shaft 93 supported at its ends in mountings 94 positioned on plates 96 extended rearwardly from the vertical end brackets 32. Shaft 93 itself is driven through, a belt 91 by a motor 98 located above the table top upon a vertical support 99. The drills'16 are adjustable transversely by sliding their backs 82, and specifically the slots 83 therein, upon the supporting seats 84 of the support 86 and may be spaced to drill holes through the board B at desired intervals. In the drawings the drills are shown in their raised or inoperative position from which they are adapted to be lowered into hole-drilling operative position by their support 86 sliding downwardly on its supporting blocks 81 under the actuation of arms IOI which pivotally connect to the ends of the support by pins I02. The means and mechanism by which the arm IIlI is moved to raise and lower drill support 86 is set forth under the following title Coordinating Means.

The coordinating means The means to form the dove tail ends and to drill the central holes must cooperate in time phase relationship and perform their functions during that time interval in which the work piece is secured in position by the clamp members, 21. The controlling and actuating means by which these various related agencies are caused to coopcrate properly will now be set forth.

Turning first to the clamps, their actuating lever arm 34 is seen to extend rearwardly-from the rock shaft 39, to which the clamp-carrying arms 28 connect, and then downwardly to carry at its lower extension a roller I06 comprising, a follower which rides upon a cam I31 mounted for rotation with a transverse shaft I66. The latter is mounted at its end in journals I09 supported by intermediate vertical frame members III.

Cam I01 is so contoured that during a part of its rotation arm 34 will be forced upwardly to pivot shaft 29 and to hold the clamps 21 in their lowered clamping position with sufficient force to prevent displacement of the work piece. During the remainder of its rotation this pressure is'not exerted and the clamps 21 are released to move upwardly from the work under the counterbalancing action of the weight of arm 34 supplemented, if desired, by suitable spring means. Shaft I08 is driven by an electric motor II4, the shaftl I6 of which connects to a speed reducing unit II1 from which extends a second shaft II8 carrying a bevel gear H3. The latter meshes with a second bevel gear I2I carried by a shaft I22 parallel to the motor shaft H6 and carrying a sprocket I23 at its opposite end. A chain I24 directly connects sprocket I23 to a second sprocket I26 fixed to shaft I68. Accordingly, cam shaft I08 rotates whenever motor H4 is energized, the latter being controlled by the operator as will be set forth.

The cutter-carrying panels or frames 42 pivot toward each other at their upper ends immediately after the clamping members 21 have moved into their operative positions and the board B is'jfirmly secured. To obtain this result use is made of coordinating means also actuated by the motor 4. As shown best in Figure 2, a pair of transverse rods I 3i are connected to straps I32 which are pivotally connected to the formed edges of the frames 42 by pivot pins I33. Framepivoting forces are exerted through the rods I3I by a T-shaped rocker element I34 in the nature of a multiple armed crank pivoted centrally at I36 upon a vertical frame member I31 in substantial alignment with the rods I3I. The inner ends of these rods extend angularly and are pivotally connected at I38 to the base of the T rocker I34. The stem of the T connects pivotally at M1 to still another rod I39, the latter extending downwardly toconnect pivotally at I42 to a vertically slidable plunger I43 positioned by a guide-member I45 fixed to frame member I31 and carrying a cam follower or roller I44 at its lower end. Plunger I43 and follower I44 are at all times forced downwardly under the action of the natural balance of the connected parts, augmented if desired, by suitable spring agencies of otal movement of thecutter-carrying frames 42 a rotatable cam I46 is provided carried by a longitudinally extending shaft. This shaft, indicated at I41, is mounted for rotation in depending brackets I48 and carries a sprocket I49 at its rear end. The latter connects through a chain- I5I to a second sprocket I52 carried by a third shaft I53 projecting from the speed reducing unit H1 in the manner of shaft H8.

It is seen then, that just as in the case of cam I01 which actuates the lever 34 and controls the position of the clamps 21, the cam I46 controlling the cutters M is rotated at all times during-the rotation of motor II4. Proper cooperation in timephase relationship is obtained by contouring the cam I46 so that the cutters 4| advance into operative position with respect to the ends of the board B during the time interval in which the board is clamped and subsequently, and after they have performed their cutting operations, are moved therefrom before the clamps are released.

'The drills 16 are also moved into operative contact with the work during the time period in which the clamps 21 are in their clamping positions. To accomplish this result, additional cams I56 are secured to the cam shaft I08 at the sides of the frame II.' A cantilever I51 is pivotally mounted upon each side of the frame by a bracket I58 carried by a vertical upright I59 and has its forward end pivotally connected at 7 ISI to the downwardly extended drill-actuating arm IOI aforementioned. The rearward end of cantilever I51 carries a roller I62 which abuts the contoured surface of cam I56 and follows its contour under the force of the weight of the connected parts supplemented, if desired, by suitable standard resilient agencies. As cams I56 are carried by the cam shaft I63 which also carries the clamp-actuating cam I61, clearly the proper contouring of cam I56 will effect the pivotal movement of cantilever I51 and so actuate the arm IUI to move the drills 16 to operative positions during the time interval in which the board is clamped as previously described.

The particular electrical connections of the driving motors 59, 98 and H4 are not of the essence of the present invention, it being sufficient that they be connected to a suitable incoming source of power, indicated generally at I6 I, andbe subject to operator control. For the latter purpose switches I62, I63 and I64 are provided mounted upon a cross member I66 extended between the brackets 32. Preferably switch I62 controls the energization of the drilldriving motor 98; switch I63 may be connected to control the motor 59 driving the cutters 4I while switch I64 may be connected to control the energization of motor H4 driving the position-controlling cams of the various coordinat ing :means.

A stillfurther feature which has considerable operating convenience to the operator comprises a slidable kicker element I1I which extends forwardly along the top platform I6 of the frame.

Kicker I1I is guided by a bracket In at the forward end thereof and is slidably supported in a double bracket I13 at the rear end of the frame. An encircling tension spring I14 is tensioned when a board 3- is positioned, the forward end of the kicker being forced rearwardly by the positioning operation, and is so held while the board is clamped in position. Upon the release of the clamps, however, the kicker moves forwardly under the actuation of spring I14 and shoves the board B forwardly upon its supporting base I8 and towards the board apron 2| from which it is readily removed by the operator.

Operation In operating the woodworking machine constructed in accordance with the present invention the operator slides a board B rearwardly upon the top platform of the machine and specifically upon the supporting base I8 until it is positioned as illustrated in the drawings, one of its ends abutting the side guide member 24 while its opposite end underlies the side guide 2-5. Movement to its operative position forces the kicker I1I rearwardly and tensions the. spring I14. Preferably the operator will have energized motors 59 and 98 by pushing the proper control buttons of the switches I62 and I63 and so the cutter elements 4| and the drills 16' will be rotating. With the work properly positioned and the cutters and drills rotating, the operator then pushes the proper button in control switch I64 whereupon motor I I4 driving the coordinating means is energized and the aforedescribed control cams I01, I46 and I55 are rotated. 'lhereupon the clamps 21, the cutters 4|, and the drills '26 move from their inoperative to their operative positions in the proper time phase relationship, that relationship comprising first the clamping of the work by the clamps 21 followed by the operation upon the board while so clamped by the drills and the cutters.

The drills 16 and the cutters 4| will be held in contact with the work for a sufficient period of time and with sufficient force to accomplish the desired work. During this time the motor I I4 rotates continuously and with it the controlling cams which effect the return of the cutters and the drills to their inoperative positions, as aforedescribed, whereupon the clamps 21 are released. Thereupon, and automatically, the kicker III under the actuation of its spring I14 shoves the board B forwardly toward theplatform or apron 2|. The board is then removed and replaced by a new board, the finished product being illustrated in Figure '1.

While the particular apparatus herein shown and described in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to'be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. In a woodworking machine, a battery of rotary end cutters having separate axes, a frame pivoted about an axis spaced from, the workin ends of said cutters and supporting same with the rotary axes of said cutters in parallel alignment for concurrent movement toward and from a work piece, a driving motor, means to convey power from said motor to said cutters in all-positions of said frame, and power means to swing said frame about said pivot axis.

2. In a woodworking machine, a battery of rotary end cutters, a frame mounting said cutters for rotation about separate spaced parallel axes, means pivotally mounting said frame for reciprocal transverse movement of said cutters toward and from a work piece, power-transmission means on said frame to rotate said cutters and including a shaft rotatable about an axis parallel to the pivotal axis of said frame, a driving motor,

means to transmit power between said shaft and I said motor in the various pivoted positions of said frame, and power means to swing said frame about said pivot axis.

3. In a woodworking machine, a battery of rotary cutters, a frame mounting said cutters for rotation about separate spaced parallel axes, means pivotally mounting said frame on an axis below said cutters for reciprocal movement of said cutters toward and from a work piece, power-transmission means on said frame to rotate said cutters and including a shaft rotating about an axis parallel to the pivotal axis of said frame and upon the opposite side of said axis from said cutters, a fixed driving motor, means including an extensible connection between said motor and said shaft to transmit power to the latter in the various positions of said frame, and power means to swing said frame about said pivot axis.

4. In a woodworking machine, a work table, spaced batteries of aligned rotary end cutters, frames each pivoted on an axis transverse to the axes of said cutters and supporting said batteries for movement toward and from opposite ends of a work piece supported on said table, draw rods connected to said frames'to exert pivoting forces thereon, and means including a cam contoured to exert forces through said rods in a predetermined time-phase relationship.

5. The structure recited in claim 4 further characterized in that said last-mentioned means also includes a crank member rotatable through a limited arc, to which said rods pivotally connect, and which is itself actuated by a sliding plunger riding in contact with said cam.

6. In a woodworking machine, a work table, a battery of rotary end cutters, a frame supporting said cutters on separate parallel axes respectively, means including spaced gears pivotally supporting said frame to enable said cutters to move toward and from a work piece on said table, toothed tracks supporting said gears for translatory movement on said frame, and means to secure said gears in a selected position on said tracks.

'1 In a woodworking machine, spaced batteries of rotary end cutters with each cutter positioned on a separate axis, a carrying frame for each battery of cutters, means including laterally shiftable means supporting each of said frames for pivotal movement, means to pivot said frames to move said cutters laterally selectively toward or from a work piece, a single driving motor, spaced drive shafts extending from said motor toward said batteries, and connecting means to transmit power between said shafts and said frames in the various pivotal positions of the latter.

SpIn a woodworking machine: a work table adapted to receive a work piece thereon; batteries of rotary dovetail end cutters, each battery comprising a plurality of said cutters arranged on separate parallel axes, said axes being substantially perpendicular tothe plane of said table; a plurality of frames, one supporting each of said batteries for concurrent movement of said cutters therein; means supporting said frames for swinging movement about an axis to move said cutters in the plane of said table, selectivelytoward or away from said work piece, whereby each of said batteries when so swung forms a series of parallel dovetailgrooves in said work piece; and actuating means having common connection with said frames and adapted to effect concurrent swinging motion thereof.

teries of rotary dovetail end cutters, each battery comprising a plurality of said cutters arranged on separate parallel axes, said axes being substantially perpendicular to the plane of said table; a plurality of frames, one supporting each of said batteries for concurrent movement of said cutters therein; means supporting said frames for oscillating movement to move said cutters in the plane of said table toward and away from said work piece whereby each of said batteries when so moved forms a series of parallel dovetail grooves in the end of said work piece; and actuating means having common connection with said frames and adapted to effect concurrent reciprocal motion thereof.

11. The structure recited in claim further characterized in that said last-named means includes: a cam; a movable member; cam follower means connected between said cam and movable member whereby to move the latter in response to movement of said cam; and links connecting said movable member to said frames.

12. In a woodworking machine: a work table; means to clamp a work piece on said table; a rotary dovetail end cutter positioned with the rotary axis thereof substantially perpendicular to said table; a frame rotatably supporting said cutter with the working end thereof substantially in the plane of said table; a pivotal mounting for said frame supporting the same for swinging movement of said cutter end toward and away from a work piece clamped on said table; a drill above said table; means mounting said drill for movement toward and from a work piece clamped on said table; and semi-automatic means including a plurality of cams interconnected to move in unison to move said clamping means into operative position and with said clamping means so positioned to swing said frame and move said cutter and concurrently to move said drill to and from working positions.

13. The structure defined in claim 12 further characterized in that upon the movement of said cutter and drill from working position said clamping means are actuated to release said work piece.

14. In a, woodworking machine: a work table; means to clamp a work piece on said table; a plurality of batteries of end cutters positioned with the axes thereof in spaced parallel alignment and adapted to form dovetail grooves in opposite ends of said work piece; a, pair of spaced frames, each rotatably supporting one of said batteries of cutters with the working ends thereof substantially in the plane of said table and adjacent ends of a work piece clamped on said table; a pivotal mounting for each of said frames supporting the same for swinging movement of said cutter ends toward and away from a work piece clamped on said table; a battery of drills above said table; means mounting said drills for movement toward and from a work piece clamped on said table; and semi-automatic means ineluding a plurality of cams interconnected to move in unison to move said clamping means into operative position and with said clamping means so positioned to swing said frames and move said batteries of cutters and concurrently to move said drills to and from operative positions.

15. In a woodworking machine, a rotary end cutter, a frame pivoted about an axis spaced from the working end of said cutter and supporting the same for swinging movement of said end toward and from a work piece, a driving motor, means to convey power from said motor to said cutter in all positions of said frame, and power means to swing said frame about said pivot axis.

16. In a woodworking machine, a rotary end cutter, a frame mounting said cutter for operative rotation, means pivotally mounting said frame on an axis below the working end of said cutter for reciprocal swinging movement of said cutter end toward and from a work piece, power transmission means on said frame to rotate said cutter and including a shaft rotating about an axis parallel to the pivot axis of said frame and on the opposite side of said axis from said cutter end, a fixed driving motor, means including an extensible connection between said motor and said shaft to transmit power to the latter in the various positions of said frame, and means to reciprocate said frame about said pivot axis.

17. In a, woodworking machine: table means adapted to receive and secure thereon a work piece; a battery of end cutters having separate axes; a frame pivoted about an axis spaced from the working ends of said cutters and supporting the same with the rotary axes of said cutters in parallel alignment and with the working ends thereof substantially in the plane of a work piece supported on said table for concurrent swinging til) movement toward and away from said work piece; a driving motor; means to convey power from said motor to said cutters in all positions of said frame; and power means to reciprocate said frame about said pivot axis thereof.

FOREST H. GILIESPIE.

REFERENCES CKTED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 283,678 Steele Aug. 21, 1883 317,876 Stevens May 12, 1885 507,020 Mansfield Oct. 17, 1893 565,213 Morgan Aug. 4. 1896 658,670 Nash Sept. 25, 1900 890,743 Winberg June 16, 1908 987,163 ONeill Mar. 21, 1911 1,197,964 Strozier Sept. 12, 1916 1,335,547 Bartholomew et al. Mar. 30, 1920 1,464,020 Anderson et al Aug. 7, 1923 1,858,677 McKnight May 17, 1932 2,000,458 Shipley May 7, 1935 2,005,647 Crouch June 18, 1935 2,290,394 Vanderveld July 21, 1942 FOREIGN PATENTS Number Country Date 113,107 Great Britain Feb. 1, 1918 

